Theta-E vs Pressure

The equivalent potential temperature (theta-E) with height in pressure coordinates is plotted.

x-axis - theta-E (K)

y-axis - pressure (mb)

red line - environmental theta-E

TEI (Theta-E Index) -the difference between the surface theta-E and the minimum theta-E in the lowest 400mb AGL

Theta-E can be used to identify potential instability, and it can be used to predict damaging winds.

Theta-E differences > 25-30 K between the surface and mid-levels (3-6km AGL), indicate a significant potential for downdrafts (Atkins and Wakimoto 1991).